Stable single phases of samarium gallium oxide (Sm3GaxOy) nano semiconductor self-assembly for supercapacitor and photocatalytic applications

Abstract

A cutting-edge approach has been attempted in the present work to develop two stable phases of samarium gallium oxide as functional materials in the form of energy storage electrodes and photocatalysts. A novel samarium gallium oxide with two stable phases has been synthesized by the gel matrix method. Their crystallinity, phase purity, and surface morphology were studied using modern analytical instruments, viz., XRD, Raman spectra, FESEM, TEM, XPS, and UV-visible spectra. The values of the band gap energy calculated using Tauc relation for Sm₃Ga₅O₁₂ and Sm₃GaO₆ are 5.06 eV and 4.74 eV, respectively. The electrodes fabricated from Sm₃Ga₅O₁₂ and Sm₃GaO₆ exhibit values of specific capacitances of 91.95 mA h g⁻¹ and 103.89 mA h g⁻¹, respectively, at 1 A g⁻¹ current density. Among the two stable phases, Sm₃GaO₆ shows significant cycling stability with a capacitive retention of 82.65% over 5000 charge/discharge cycles. The prepared asymmetric supercapacitor with Sm₃GaO₆ as an active material exhibits an improved energy and power density of 11.72 W h kg⁻¹ and 312.5 W kg⁻¹, respectively, with a coulombic efficiency of 97.17% after 5000 cycles. The results obtained from photocatalytic studies infer that the methylene blue dye was efficiently degraded by Sm₃Ga₅O₁₂ and Sm₃GaO₆ with 92% and 97%, respectively, within 120 min of light irradiation. Sm₃GaO₆ functions as a better and more efficient photocatalyst for degrading methylene blue dye, with a higher efficiency and a higher degradation rate of 0.0273 min⁻¹. The results obtained from electrochemical and photocatalytic studies infer that both phases of samarium gallium oxide can be considered as potential materials for energy storage and environmental remediation applications.